Isaiah Berlin maintains that there are two distinct forms of freedom or liberty: negative and positive. Berlin’s principal claim is that negative liberty does not require that the self be somehow separate from the empirical world (causally aloof, or an originator of causal chains). My principal claim is that to be an agent is to be committed to a separation of self in this sense, thus that the self for its very being requires to possess a species of positive liberty. This conception proceeds in part from Immanuel Kant’s claim that there is a separation between spontaneity and receptivity. Commitment to this assertion allows there to be an understood distinction between the self as a spontaneous self-active agent that makes choices, and the self as a mere reactionary brute that does what it does by biological imperatives. In this thesis, I defend the view that negative liberty is subsumed under positive liberty: you cannot have the former without the latter. I am therefore taking a rationalist stance towards Berlin’s thinking. My methodology is to bring into consideration two perspectives upon the underlying normative principles within the space of reason. The first is of Kant’s understanding of the principle of responsibility and the activity of spontaneity; the second is John McDowell’s understanding of that principle and activity. The key claim of this thesis is that Berlin misunderstands what it is to be a chooser. To be a chooser is to be raised under the idea that one is an efficient cause; human children are brought up being held responsible for their reasons for acting. This principle allows mere animal being to be raised into the space of reason, where we live out a second nature in terms of reason. Using their conclusions I further investigate Berlin’s understanding of conceptual frameworks, taking particular interest in historic ‘universal’ conceptions that shape human lives. He too finds that that we are choosers is necessary for what it is to be human. I take his conclusion, and suggest that if he had had a clear understanding of the space of reason, the historic claim that we have choice would find a more solid footing in the principle of that space, in that we are responsible for our actions. I conclude that the upshot of understanding the ‘I’ as an originating efficient cause is that we treat ourselves as free from a universal determinism that Berlin himself disparages; and that the cost to Berlin is that all choice is necessarily the activity of a higher choosing self. It is part of a Liberal society’s valuing, by their societal commitment to, the ideology of raising our children to understand themselves as choosers, that we have choice at all. This is irrespective of whether that which fetters choice is internal or external to the agent, or of whether having self-conscious itself requires such a cultural emergence of second nature.